1. Field of the Invention
The present invention relates generally to treadmills, and more particularly to a treadbase supporting structure for treadmill.
2. Description of the Related Art
A conventional treadmill, as shown in FIG. 1, is generally composed of a treadbase 1, a base frame 2, and a support 3 connected between the base frame 2 and the treadbase 1 for supporting the treadbase 1 to be mounted fixedly on the base frame 2 in a non-operative position. The support 3 includes an outer tube 3a, an inner tube 3b fitted in the outer tube 3a, a tensile spring (not shown) mounted inside the outer tube 3a, and a tightening screw 4 mounted outside the outer tube 3a. When the treadbase 1 is turned from an operative position to the non-operative position, the tightening screw 4 is screwed inwards and contacts against the periphery of the inner tube 3b to stop the inner tube 3b from further moving inside the outer tube 3a however, the tightening force of the tightening screw 4 is weak such that the inner tube 3b is subject to fall inside of the outer tube 3a and the treadmill is structurally defective. Furthermore, while changing the position of the treadbase 1, a user must hold the treadbase 1 with one hand, and then screw up or loosen the tightening screw 4 with the other hand, i.e. the user fails to adjust the treadbase 1 between the operative position and the non-operative position with one single hand.
FIGS. 2 and 3 show another treadmill folding structure according to the prior art. According to this design, a retractable support connecting between the base frame 8 and the treadbase 5 is composed of a stop member 6 and a retractable rod 7. The retractable rod 7 is composed of a tubular outer rod member 7a and a piston 7b. The tubular outer rod member 7a has a first end pivoted to the treadbase 5, and a second end having a stop flange 7c. The stop member 6 is a hollow cylindrical member having a notched stop edge 6a in a top end thereof. The piston 7b has an end connected to the inside of the stop member 6, and the other end inserted in the tubular outer rod member 7a. When the treadbase 5 is set in the non-operative position, the stop flange 7c is stopped at the notched stop edge 6a (see FIG. 3A), and therefore the treadbase 5 is supported in the non-operative position (see FIG. 2). When changing the treadbase 5 from the non-operative position to the operative position, disengage the stop flange 7c from the notched stop edge 6a to keep the tubular outer rod member 7a in alignment with the piston 7b coaxially (see FIG. 3B), and then the treadbase 5 is lowered. However, treadmill is structurally defective. When a child touched the stop member 6 accidentally, the notched stop edge 6a may be forced away from the stop flange 7c, thereby causing the treadbase 5 to fall.